The present invention relates to a mobile vehicular apparatus which includes an aerial platform or cabin and manipulators that are mounted on the distal end of a telescopic boom, which can be turned, moved vertically, and extended and contracted to move the platform or cabin carrying the operator to a desired three-dimensional position, and more particularly to a system for controlling movement of the telescopic boom.
Various mobile vehicular apparatus with aerial platforms or cabins have been proposed so far. For example, Japanese Laid-Open Utility Model Publication No. 63(1988)-173193, discloses a mobile vehicular apparatus which has a manipulator and a platform for carrying an operator who controls the manipulator on the distal end of a boom. The platform is equipped with a plurality of manually operated control levers which can be manually operated on by the operator to control operation of the manipulator and the boom. However, even if the operator uses both hands, only two kinds of operation can be performed at a time, and hence the efficiency is poor.
In many mobile vehicular apparatus, only a platform is attached to the distal end of a boom, with no manipulator provided. Such mobile vehicular apparatus are often used to handle electric cables supported on poles. While an electric cable is being repaired, serviced, or otherwise handled, the operator is required to use his both hands. Therefore, in order to control operation of the boom, the operator has to interrupt the process of handling the electric cable and then operate the boom, resulting in poor efficiency.
U.S. Pat. No. 3,866,713 issued to Carpenter et al. discloses a mobile vehicular apparatus with a platform on the distal end of a boom. The platform has control foot treadles for controlling operation of the boom and also the position of the platform. The disclosed mobile vehicular apparatus is typically used to harvest tree borne fruit. The operator in the platform manipulates the foot treadles with his feet for the control of the position of the platform, so that the operator can exclusively use the hands to harvest tree borne fruit.
With the disclosed mobile vehicular apparatus, however, the foot treadles are merely juxtaposed on the floor of the platform, and the directions in which the foot treadles are manipulated do not correspond to the directions in which the platform is moved. The operator is therefore required to be skilled for quick and efficient manipulation of the foot treadles. If the operator manipulates the foot treadles in error, then the platform may be moved in a direction in which the operator did not intend to move the platform. Moreover, operator-initiated movement of the foot treadles is transmitted as a pneumatic pressure to hydraulic pressure control valves for controlling movement of the platform. Since air pipes are required, the entire control system is complex and large in size. Another problem is that the accuracy of controlling operation is relatively poor because compressible air is used as a control signal transmitting medium.